ALSA: pcm: Preprocess PAUSED or SUSPENDED stream before PREPARE

Calling PREPARE ioctl to the stream in either PAUSED or SUSPENDED
state may confuse some drivers that don't handle the state properly.
Instead of fixing each driver, PCM core should take care of the proper
state change before actually trying to (re-)prepare the stream.
Namely, when the stream is in PAUSED state, it triggers PAUSE_RELEASE,
and when in SUSPENDED state, it triggers STOP, before calling prepare
callbacks.
Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/pcm_native.c

@@ -1684,6 +1684,17 @@ static int snd_pcm_prepare(struct snd_pcm_substream *substream,
 	else
 		f_flags = substream->f_flags;
 
+	snd_pcm_stream_lock_irq(substream);
+	switch (substream->runtime->status->state) {
+	case SNDRV_PCM_STATE_PAUSED:
+		snd_pcm_pause(substream, 0);
+		/* fallthru */
+	case SNDRV_PCM_STATE_SUSPENDED:
+		snd_pcm_stop(substream, SNDRV_PCM_STATE_SETUP);
+		break;
+	}
+	snd_pcm_stream_unlock_irq(substream);
+
 	return snd_pcm_action_nonatomic(&snd_pcm_action_prepare,
 					substream, f_flags);
 }